The present invention relates to wrapping materials that include a Z-lock system to releasably attach separate wrapping portions of a predetermined length that are held together and released at their lateral ends, and methods of using and assembling the wrapping material. Each wrapping portion constitutes at least one complete wrapping cycle. A complete roll of wrapping material comprises several wrapping portions, which are held and released at their lateral ends. Lateral ends of each wrapping portion are formed into a Z-shape to produce the Z-lock system. The Z-lock system holds the wrapping portions together during manufacturing but also easily releases the wrapping portions at the completion of a wrapping cycle. At the completion of the wrapping cycle, the lateral end of at least one wrapping portion when released retains an adhesive layer that seals the item being wrapped.
In conventional wrapping operations whenever an item (round, square, or other shaped bale) is wrapped with film supplied from a wound roll, the film must be adhered to the film layer under it in order to securely wrap an item. At present, it is customary to use film that is tacky on one side, and along its entire length to securely wrap the item.
There are a number of existing methods for manufacturing wrapping material to include film with a tacky surface on one side. Some examples include the use of film that can be manufactured by coating with a layer of adhesive, creating electrostatic charges, co-extrusion or other method known in the field of wrapping. However, the disadvantage in all these methods is that when the adhesive is applied on one entire side, the level of adhesion is not high enough since the film must still be allowed to unwind during wrapping of an item. To this end, there are significant limitations on the level of adhesion that can be achieved, making it particularly difficult to securely wrap an item especially at the tail-end of the wrapping material.
Moreover, there are various forces exerted on the wrapping material, which cause the wrapping material, particularly the tail-end, to come loose after an item is wrapped. Shearing and peeling are examples of some of these forces exerted on wrapping material during wrapping. In addition, if the wrapping material is used outdoors, exposure to the extremes of temperature, moisture and especially wind will cause additional problems with adhesion of the tail-end of the wrapping material.
To overcome these problems, methods have been suggested for maintaining a high level of adhesion for the tail-end of wrapping material when wrapping under extreme conditions. One method of addressing the separation problem of the wrapping material is to produce wrap that includes wrapping portions of a fixed length having very strong adhesive qualities at needed locations along the wrapping material. Although this type of wrapping material tends to have increased adhesive qualities, especially at the tail-end of the wrapping cycle, problems have been experienced with the portions of the wrap sticking to each other when wound onto rolls during the manufacturing process.
With the foregoing in mind, the methods and material of the present invention provide a solution to the problems noted above in the prior art.
In accordance with an aspect of the present invention, the inventive wrapping material uses an adhesive and at least one releasable layer that covers and protects the adhesive while the wrapping material is on a roll. The releasable layer can be used to prevent different wrapping layers from sticking to each other during the manufacturing process. However, when the wrapping material is unwound, the releasable layer will peel away from the adhesive layer at the end of a wrapping cycle. More specifically, when a wrapping portion of wrap is unwound the releasable layer peels away and completely separates from the adhesive layer. The peeling of the protective layer exposes the adhesive layer for sealing the item being wrapped at the completion of a wrapping cycle. Additionally, the releasable layer remains adhered harmlessly to the continuation of the wrapping material still on the roll for the next wrapping application or cycle. In this way, the wrapping portions that remain on the roll are always protected from the adhesives used in the wrapping process, no matter what the diameter of the roll.
In accordance with a further aspect of the present invention, a method is provided which includes the use of wrapping portions of a predetermined length, wherein each portion has an adhesive layer at a lateral end for gluing and securing the tail-end of the wrapping portion.
In accordance with a further aspect of the present invention, the method is provided which includes connecting wrapping portions using a Z-lock, which facilitates the attachment/connection of two different wrapping portions using strong glue while still allowing easy peeling and separation of the Z-lock at the desired time in a wrapping cycle.
In accordance with a further aspect of the present invention, a method is provided which includes connecting wrapping portions using a Z-lock that includes the use of at least one laminate portion.
In accordance with a further aspect of the present invention, a laminate with at least one adhesive is placed on a wrapping portion at the tail-end of the material after being folded back into a V-fold. The tail-end of another wrapping portion is then laid on top of the V-fold to create the Z-lock. The laminate can then be separated between a releasable layer and an adhesive layer by using a peeling action at the end of the wrapping cycle.
In accordance with another aspect of the invention, the wrapping material includes a Z-lock with wrapping portions that terminate exactly even with the end of an adhesive layer.
In accordance with another aspect of the invention, a method is provided which includes stopping a roll of wrapping material while the element being wrapped continues to move. As a result, the tail-end of a wrapping portion continues to be pulled in the direction of the item being wrapped putting pressure on the Z-lock. As pressure continues to be exerted on the Z lock, the Z-lock separates as the releasable layer peels away from the adhesive layer. The adhesive layer, which is located at the end of the portion, is exposed only at the moment the adhesive layer meets the item being wrapped at the completion of the wrapping cycle.
In accordance with a further aspect of the invention, the releasable layer remains at the end of the portion of wrapping material still on the roll. This releasable layer serves to thicken the beginning of the next portion and improves the feeding of the next portion into a baler, or other type of wrapping equipment.
In accordance with another aspect of the invention, the laminate used in the Z-lock includes several different layers of material.
In accordance with another aspect of the invention, a method is provided which includes lengthening the folds of the Z-lock in order to prevent the possibility of premature separation.
In accordance with another aspect of the invention, the Z-lock includes at least two adhesive areas laterally separated from each other to prevent premature separation.
In accordance with another aspect of the invention, a method is provided which includes the use of double-sided adhesive strips with a lower rate of adhesion on one side of the Z-lock.